1. Field of the Invention
This invention relates to electronic circuits and, more particularly, to systems that multiplex and demultiplex video signals so that the signals may be recorded and played back at another time.
2. Description of the Prior Art
Man has invented simulators and other training devices to teach students to use and operate various types of equipment without undergoing the dangers that are inherent in the equipment's actual operation. It is a great deal safer to learn how to fly an aircraft on the ground in a simulator than in an actual aircraft in the air.
People have sense organs which react to physical stimulation. These sense organs are continuously stimulated by a simulator. After the student performs some maneuver on the simulator, the simulated flight usually continues and, upon the conclusion of the flight, the student usually forgets what he has done to perform a particular maneuver of the aircraft. Thus, it would be beneficial to the student's training if the visual picture that the student sees and the readings of the simulated aircraft's instruments could be recorded during the simulated flight so that the student may play back the recorded information and learn from his mistakes. In the past, one of the only ways that the foregoing could be accomplished was to have one moving picture camera or video tape recorder record what the pilot sees outside the aircraft and have a second moving picture camera or video tape recorder record the readings that appear on the aircraft's instruments. When the student and his instructor wanted to study the simulated flight, each of the recordings were played back on a different motion picture projector or video tape recorder. The nature of the recorders and playback devices was such that when the two recordings were attempted to be played back at the same time, the recordings would be out of synchronization. Hence, the student would receive little training value viewing the recordings since he would not see the correct instrument readings corresponding to what he saw outside of the cockpit of the simulated aircraft. Thus, in the prior art, the student's simulated flight was not recorded where simultaneous playback was required.